Keto-acid chloride and diketone intermediates in the acylation of ferrocene by arylene bis-acid chlorides. Crystal and molecular structure of 4-ferrocenylcarbonyl-4′-chlorocarbonylbiphenyl: intermolecular association by means of strong C–H⋯O hydrogen bonds and π⋯π stacking interactions

Abstract

Acylation of ferrocene with arylene bis-acid chlorides yields deep-red polymeric products. However, under controlled conditions two types of intermediate can be isolated and characterised: the keto-acid chlorides FcCO(arylene)COCl 1 [Fc=(C 5H 5)Fe(C 5H 4); a arylene=4,4′-C 6H 4C 6H 4, b arylene=1,3-C 6H 4, c arylene=1,4-C 6H 4], followed in the case of 1a and 1b by the diketones FcCO(arylene)COFc 2a and 2b, although no conversion of 1c to 2c occurs. Similarly, use of 1,3,5-benzenetricarbonyl trichloride yielded 1,3,5-C 6H 3(COFc) 3. In the crystal structure of 1a, there are four independent molecules: pairs of molecules are linked into dimers by strong C–H⋯O hydrogen bonds, and these dimers are linked into chains by π⋯π stacking interactions.